Under the assumption of MFV, supplemented
by \(g_v = g_u = g_d = g_\ell \) , the most relevant couplings
between DM and the SM arising from
(REF ) and () are those
that involve top quarks. Two main strategies have been
exploited to search for scalar and pseudoscalar interactions
of this type using LHC data. The first possibility consists in
looking for a mono-jet plus missing energy signal \({E}_T + j\) , where the mediators that pair produce DM are radiated
from top-quark loops [1]},
while the second possibility relies on
detecting the top-quark decay products that arise from the
tree-level reaction \({E}_T + t \bar{t}\)  [2]}.
In the first paper [1]} that discussed the \({E}_T + j\)  signal the effects of DM fermions coupled to heavy-quark loops were characterized in terms
of effective higher-dimensional operators, i.e. with mediators being integrated out. The effects of dynamical scalar and pseudoscalar messengers
in the \(s\) -channel mediating interactions between the heavy quarks in the loop and DM were
computed in characterizing the LHC signatures for DM searches in [4]}, [5]}, [6]}, [7]}, [8]}.
